Acoustic pulsejet helmet

ABSTRACT

A pulsejet is provided that includes an inlet, an exhaust nozzle, and a combustion chamber between the inlet and the exhaust nozzle. The pulsejet additionally includes a flow-turning device positioned over an end of the inlet. The flow turning device forms an air flow pathway (AFP) having a substantially 180° turn. The 180° turn aligns a direction of exhaust exiting the combustion chamber through the inlet along a positive axial thrust line and substantially parallel with exhaust exiting the combustion chamber through the nozzle.

FIELD OF INVENTION

The invention relates generally to pulsejet engines and moreparticularly to valve-less pulsejet engines that direct all thrustforces along an axis of positive thrust.

BACKGROUND OF THE INVENTION

Pulsejet engines are extraordinarily simple devices that provide aninexpensive means to provide thrust for an aircraft. Most pulsejetstypically include a mechanical valve to prevent air and thrust fromescaping through the inlet of the pulsejet when combustions occur in thecombustion chamber of the pulsejet. A main disadvantage of thesepulsejets is that they generally have a low efficiency and themechanical valves have a limited durability. Some more recent pulsejetdesigns have implemented a pneumatic air inlet valve that eliminates thedurability problem of the mechanical inlet valve. The pneumatic airvalve generally injected air into a throat section of the inlet nozzleas the fuel in the combustion chamber ignited. This created a highpressure zone at the inlet nozzle throat that prevented thrust from thefuel combustion from escaping out the inlet. Notwithstanding the removalof the mechanical valve and greatly improved durability, implementationof the pneumatic air valve required supplemental equipment to provideand inject the air into the inlet nozzle of the pulsejet. And, theamount and complexity of the additional supplemental equipmentsignificantly increases as the number of pulsejets included in a systemmultiply.

Additionally, a typical bank of pulsejets would include a plurality ofround pulsejets aligned in columns and rows. In this configuration, thepulsejets where interconnected using a webbing of orthogonal walls thatformed a grid of square compartments with a single pulsejet within eachcompartment. The interconnected webbing adds considerable weight to eachpulsejet bank and the space created by round pulsejets in squarecompartments created gaps that could allow a portion of the thrustgenerated by each pulsejet to escape in the wrong direction.

A need therefore exists for a pulsejet engine design that reducesmaintenance, weight and complexity of existing designs while increasingthe thrust efficiency.

BRIEF SUMMARY OF THE INVENTION

In various embodiments of the present invention, a pulsejet is providedthat includes an inlet, an exhaust nozzle, and a combustion chamberbetween the inlet and the exhaust nozzle. The pulsejet additionallyincludes a flow-turning device positioned over an end of the inlet. Theflow turning device forms an air flow pathway (AFP) having asubstantially 180° turn. The 180° turn aligns a direction of exhaustexiting the combustion chamber through the inlet along a positive axialthrust line and substantially parallel with exhaust exiting thecombustion chamber through the nozzle.

In various other embodiments, a method for providing vertical take offand landing propulsion for an aircraft is provided. The method includesproviding at least one valve-less pulsejet integrated within a fuselageof the aircraft. The pulsejet includes a body having an inlet, anexhaust nozzle, a combustion chamber between the inlet and the exhaustnozzle. The method additionally includes positioning a flow-turningdevice over an end of the body to form an air flow pathway (AFP) havinga substantially 180° turn. The 180° turn aligns a direction of exhaustexiting the combustion chamber through the inlet to be substantiallyparallel with exhaust exiting the combustion chamber through the nozzlealong a positive axial thrust line.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiments of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention. Furthermore, the features, functions, and advantages ofthe present invention can be achieved independently in variousembodiments of the present inventions or may be combined in yet otherembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and accompanying drawings, wherein:

FIG. 1A is an isometric cross sectional view of the valve-less pulsejetengine, in accordance with various embodiments of the presentinventions;

FIG. 1B is a cross sectional side view of the pulsejet engine shown inFIG. 1A;

FIG. 2 is a cross sectional side view of the pulsejet engine shown inFIG. 1B including an elongated straight inlet section, in accordancewith various embodiments of the present invention;

FIG. 3A is a cross sectional side view of the pulsejet engine shown inFIG. 1B including a cruciform shaped combustion chamber, in accordancewith various embodiments of the present invention;

FIG. 3B is a cross sectional top view of the cruciform shaped combustionchamber shown in FIG. 3A, along line 3B-3B, having a flow-turning devicepositioned over an inlet of the pulsejet engine;

FIG. 4 is an isometric view of the pulsejet engine shown in FIG. 1Amounted within an augmentor cell, in accordance with various embodimentsof the present invention;

FIG. 5 is an isometric view of a plurality of the pulsejet engines shownin FIG. 1 A mounted within a multi-bay augmentor to form a pulsejetaugmentor bank, in accordance with various embodiments of the presentinvention;

FIG. 6 is an isometric view of a linear acoustic pulsejet (LAP), inaccordance with various embodiments of the present invention;

FIG. 6A is a cross-sectional view of the LAP shown in FIG. 6, along lineA-A;

FIG. 6B is a side view of the LAP shown in FIG. 6;

FIG. 6C is an isometric view illustrating a plurality of dividers in alinear helmet of the LAP shown in FIG. 6;

FIG. 7 is an isometric view of the LAP shown in FIG. 6 having undulatingside panels, in accordance with various embodiments of the presentinvention;

FIG. 7A is an end view of the LAP shown in FIG. 7;

FIG. 8 is an isometric view of the LAP shown in FIG. 6 mounted in a LAPaugmentor, in accordance with various embodiments of the presentinvention;

FIG. 8A is an isometric view of the LAP shown in FIG. 8 includingauxiliary inlets in the LAP augmentor, in accordance with variousembodiments of the present invention;

FIG. 9 is an isometric view of the LAP shown in FIG. 6 including doublewalled intercostals, in accordance with various embodiments of thepresent invention;

FIG. 9A is a cross-sectional view of the LAP shown in FIG. 9, along lineA-A;

FIG. 9B is the cross-section shown in FIG. 9A having walls of doublewalled intercostals forming rounded corner for the pulsejet cells; and

FIG. 9C is an isometric view illustrating a plurality of double-walleddividers in the linear helmet of the LAP shown in FIG. 9.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the invention,its application or uses. Additionally, the advantages provided by thepreferred embodiments, as described below, are exemplary in nature andnot all preferred embodiments provide the same advantages or the samedegree of advantages.

FIGS. 1A and 1B are cross sections of the valve-less pulsejet engine, inaccordance with various embodiments of the present inventions. Thepulsejet engine will simply be referred to herein as the pulsejet 10.The pulsejet 10 includes a body 12 having an inlet 14, an exhaust nozzle18, a combustion chamber 22 between the inlet 14 and the exhaust nozzle18, and a flow turning device 26, herein referred to as a helmet 26,positioned over an end of the inlet 14. An air flow pathway (AFP) 30through which air flows into and out of the pulsejet 10 is formedbetween a side wall 34 of the helmet 26 and an outer portion of thepulsejet 10 near combustion chamber 22 and the inlet 14. In variousembodiments, as shown in FIG. 1, the AFP 30 is an annular AFP. Inoperation of the pulsejet 10, a propulsion cycle comprises an air intakephase, a compression phase and a combustion phase. Generally, during thecompression phase, intake air flows through the AFP 30 in the Adirection and enters the inlet 14. The intake air is mixed with fuelinjected into the combustion chamber 22 and detonated during acombustion phase due to pressure created inside the combustion chamber22. More particularly, initially air is injected into the combustionchamber 22 to mix with the injected fuel and an ignition source isprovided to cause the air/fuel mixture to combust during at least oneinitial combustion phase. Each air/fuel combustion produces exhaustthrust that discharges from the exhaust nozzle 18 in B direction. Thisexhaust thrust will be referred to herein as the primary exhaust orprimary thrust. Each combustion phase additionally produces exhaustthrust that exits the combustion chamber 22 through the inlet in the Cdirection. Thrust exiting the combustion chamber 22 through the inlet 14of the pulsejet 10 will be referred to herein as secondary exhaust orsecondary thrust.

Reflective pressure waves generated by each air/fuel combustion createpressures within the combustion chamber 22 that cause subsequentair/fuel mixtures to detonate during subsequent propulsion cycles. Thepropulsion cycle of a valveless pulsejet, such as pulsejet 10, isdescribed in issued U.S. Pat. No. 6,824,097, titled “Vertical TakeoffAnd Landing Aircraft” and issued Nov. 30, 2004, which is hereinincorporated by reference in its entirety. In various embodiments, thehelmet 26 forms approximately a 180° turn section 36 in the AFP 30 thatturns the secondary exhaust thrust effectively 180° such that both theprimary and secondary thrusts flow along an axis of positive thrust inthe B direction that is approximately parallel with a pulsejet 10longitudinal centerline C. Therefore, negative thrust problems of knownpulsejet engines are eliminated without the need for additional devicesor equipment, such as mechanical valves or large high pressure airinjection systems. Additionally, the AFP 30 formed by the helmet 26ensures that a path followed by inlet acoustic expansion/reflectionwaves is such that they meet returning nozzle acousticexpansion/reflection waves in the combustion chamber 22 to initiate newcycle ignition. After ignition, expansion waves exit the pulsejet 10 viathe inlet 18 and the exhaust nozzle 18 causing reflection waves totravel through the inlet 14 and the nozzle 18 toward the combustionchamber 22. However, prior to ignition cool air is taken into thecombustion chamber via the AFP 30, such that the inlet 14 maintains amuch cooler temperature than the exhaust nozzle 18, which duringoperation can obtain a temperature of approximately 1500° F. Therefore,since the speed and distance traveled of the expansion/reflection waveis a function of temperature, it takes the expansion/reflection wavesmuch more time to traverse through the cooler, shorter inlet 14 thanthrough the hotter, longer nozzle 18. Thus, the inlet acousticexpansion/reflection waves meet returning nozzle acousticexpansion/reflection waves to provide self-sustained operation, i.e.self-sustained repetitive propulsion phases, of the pulsejet 10 at ornear a resonant frequency.

Additionally, in various embodiments helmet 26 has an outside diameter Dthat is approximately 100% to 125% of an outside diameter F of thecombustion chamber 22. Therefore, an overall diameter of installation ofthe pulsejet 10 is minimized such that installation of the pulsejet 10in an aircraft, e.g. a VTOL aircraft, requires only a minimal amount ofspace. The helmet 26 and the inlet 14 are sized such that the entire AFP30, including the 180° turn section 36, provides as much airflow gap aspossible to increase the inlet airflow and improve performance ofpulsejet 10. In various embodiments, the helmet 26 is formed such thatthe AFP 30 increases in area near a lip 37 of the helmet side wall 34.This allows more air to be drawn into the pulsejet and diffuses thesecondary exhaust as it exits the AFP 30.

Referring to FIG. 2, in various embodiments the pulsejet 10 includes anelongated straight inlet section 40 extending from the inlet 14. Theinlet section 40 provides a specified aspect ratio, i.e. inlet sectionlength over inlet section diameter, for stable operation of thepulsejet. 10. The straight inlet section 40 creates an AFP 30 having anexpanding area ratio as helmet side wall 34 extends toward thecombustion chamber 22 and nozzle 18. That is, an annular area betweenthe exterior of the inlet section 40 and the interior of the helmet sidewall 34 increases from the open end, or inlet 14, of the inlet section40 to an open end of the helmet side wall 34. Therefore, the expandingarea ratio provide increase and improved air flow into the pulsejet 10during the compression phase and also provides diffusion of secondaryexhaust during the combustion phase that reduces or eliminates backpressure caused by a restrictive AFP 30. The length-to-diameter ratio ofthe inlet section 40 is configured to acoustically tune the inletsection 40 such that resonant waves will sustain operation, i.e.combustions, of the pulsejet 10 with no other combustion controls thanfuel. That is, further artificial ignition, e.g. a glow plug or sparkplug, is not required. A key critical resonant length P of the inletsection 40 extends from an inlet plane in the combustion chamber 22 tothe lip 37 of the helmet side wall 34. The length P control the resonantfrequency of the reflection waves that combust the air/fuel mixture inthe combustion chamber 22. Furthermore, the straight inlet section 40allows the outside diameter D of the helmet 26 to be minimized toprovide a reasonably compact design that reduces the overall diameter ofinstallation.

Referring now to FIGS. 3A and 3B, in various embodiments, the combustionchamber 22 has a non-cylindrical shape. For example, the combustionchamber 22 can have an elongated cruciform or star-like shape. Thecruciform combustion chamber 22 includes a plurality of linear apexes 41and linear valleys 43. The spaces between the interior of the helmetside wall 34 and the valleys 43 create a plurality of AFPs 30 thatprovide effectively unimpeded air intake flow and secondary exhaustflow. This reduces or eliminates back pressure caused by a restrictiveAFP 30. In addition to providing the AFP 30s, the cruciform shapedcombustion chamber 22 allows the outside diameter D of the helmet to beapproximately equal to the outside diameter F of combustion chamber 22at the widest point, i.e. from one apex peak 41 to an opposing apex peak41. Therefore, the overall diameter of installation can be greatlyreduced.

Referring now to FIG. 4, in various embodiments, the pulsejet 10 ismounted within an augmentor cell 38. The augmentor cell 38 includes apair of opposing entraining walls 42 adapted to entrain ambient air withthe pulsejet primary and secondary exhausts to maximize propulsionthrust from the pulsejet 10. For clarity of illustration, one of theentrainment walls 42 has been removed from FIG. 2. The entrainment walls42 can have any shape suitable to entrain the ambient air. For example,the entrainment wall 42 can be flat or curved, as shown in FIG. 4. Theaugmentor cell 38 additionally includes a pair of opposing side panels46 connected to and substantially orthogonally between the entrainingwalls 42. The pulsejet 10 can be mounted within the augmentor cell 38using any suitable mounting means, component, device or structure. Forexample, the pulsejet 10 can be mounted to one or more of the augmentorcell walls 42 and/or the side panels 46 using one or more of fairings50. Although the fairings 50 are shown to extend along the entire lengthof the pulsejet 10, the fairing 50 can extend along a portion of eachpulsejet 10 without altering the scope of the invention. In variousembodiments, the side panels 46 include a plurality of apertures 54adapted to allow a portion of the entrained air and the primary andsecondary exhausts to exit the augmentor cell 38 in a cross flowdirection G. It should be understood that any of the various embodimentsdescribed above in reference to FIGS. 1A, 1B, 2, 3A and 3B can beincorporated in the pulsejet augmentor cell 38.

Referring to FIG. 5, in various embodiments a plurality of pulsejets 10are mounted within a multi-bay augmentor 58 to form a pulsejet augmentorbank 62. The pulsejet augmentor bank 62 includes a pair of opposingentraining walls 66 and a plurality of intercostals 70 connected to andsubstantially orthogonally between the entraining walls 66. For clarityof illustration, one bank entrainment wall 66 has been removed from FIG.3. The plurality of intercostals 70 effectively subdivide the pulsejetaugmentor bank 62 into a plurality of pulsejet augmentor bays 74 similarto the augmentor cell 38 described above with reference to FIG. 2.Analogous to the entrainment walls 42 of the augmentor cell 38 in FIG.2, the bank entrainment walls 66 are adapted to entrain ambient air withthe primary and secondary exhausts of each pulsejet 10 to maximizepropulsion thrust from the pulsejets 10. Additionally, the bankentrainment walls 66 can have any shape suitable to entrain the ambientair, e.g. flat or curved, and each of the pulsejets 10 can be mountedwithin the respective augmentor bay 74 in any suitable manner, e.g.using one or more fairings such as fairing 50 shown in FIG. 4.Furthermore, in various embodiments, the bank intercostals 70 include aplurality of apertures 78 adapted to allow a portion of the entrainedair and the primary and secondary exhausts of each pulsejet 10 to exitthe respective augmentor bay 74 in a cross flow direction G. Therefore,the apertures 78 permit equalization of flow between each of thepulsejet primary and secondary exhaust flows such that any of thepulsejets 10 within the pulsejet augmentor bank 62 that operate above orbelow a nominal operating condition are equalized with the remainingpulsejet 10 primary and secondary exhaust flows. It should be understoodthat any of the various pulsejet 10 embodiments described above inreference to FIGS. 1A, 1B, 2, 3A and 3B can be incorporated in thepulsejet augmentor bank 62.

Exemplary embodiments of the pulsejet augmentor cell 38 and the pulsejetaugmentor bank 62 are described in issued U.S. Pat. No. 6,824,097,titled “Vertical Takeoff And Landing Aircraft”, issued Nov. 30, 2004,which is herein incorporated by reference in its entirety.

Referring now to FIGS. 6, 6A, 6B, 7 and 7A a linear acoustic pulsejet(LAP) 72 includes a body 82 having a first side panel 86 and an opposingsubstantially parallel second side panel 90. A plurality ofsubstantially parallel intermediate walls, or intercostals 94, areconnected to and substantially orthogonally between each of the firstand second side panels 86 and 90 to create a plurality of pulsejet cells98 in an interior of the body 82. The LAP 72 additionally includes aninlet section 102 that forms an inlet for each pulsejet cell 98, anexhaust nozzle section 106 that forms an exhaust nozzle for eachpulsejet cell 98, and a combustion chamber section 110 that forms acombustion chamber between the inlet and the exhaust nozzle of eachpulsejet cell 98. The inlet, exhaust and combustion sections 102, 106and 110 are best shown in FIG. 6B. The inlet, exhaust nozzle andcombustion chamber of each pulsejet cell 98 will be respectivelyreferred to herein as inlet 102′, exhaust nozzle 106′ and combustionchamber 110′. The LAP 72 further includes a linear inlet helmet or inletcap 114 positioned over and connected to an end of the inlet section102. A linear air flow pathway (LAFP) 118, best shown in FIG. 7A, isformed between opposing walls 120 of the linear helmet 114 and the inletsection 102 through which air flows into and out of each pulsejet cell98. For clarity of FIGS. 6, 6A, 6C and 7, the side panels 86 and 90, andthe intercostals 94 are illustrated by a single solid or dashed line.However, it should be understood that the side panels 86 and 90, and theintercostals 94 have a thickness sufficient to withstand the heat,stresses and forces the panels 86 and 90, and the intercostals 94 areexposed to during operation of the aircraft and the LAG 72.

In operation of the LAP 72, each pulsejet cell 98 operates independentlyof the other pulsejet cells 98. For each pulsejet cell 98 one propulsioncycle comprises an air intake phase, a compression phase and acombustion phase. Generally, during the compression phase, intake airflows through the LAFP 118 in the H direction and enters the inlets 102′of the respective pulsejet cell 98. The intake air is mixed with fuelinjected into the respective pulsejet cell 98 combustion chambers 110′and detonated during the combustion phase. Initially, air is injectedinto each combustion chamber 110′ to mix with the injected fuel and anignition source is provided to cause the air/fuel mixture to combustduring at least one initial combustion phase. Reflective pressure wavesgenerated by each air/fuel combustion create pressures within thecombustion chambers 110′ that cause subsequent air/fuel mixtures todetonate during subsequent propulsion cycles. That is, furtherartificial ignition, e.g. a glow plug or spark plug, is not required.

Each air/fuel combustion produces exhaust thrust that discharges fromthe respective exhaust nozzles 106′ in an I direction and exhaust thrustthat exits the respective combustion chambers 110′ through therespective inlets 102′ in the J direction. Exhaust thrust dischargingvia each pulsejet cell nozzle 106′ will be referred to herein as the LAPprimary exhaust thrust or primary thrust and exhaust thrust exiting viathe pulsejet cell inlets 102′ will be referred to herein as the LAPsecondary exhaust thrust or secondary thrust. In various embodiments,the linear helmet 114 forms the LAFP 118 to have an approximately 180°turn section 116. The 180° section effectively turns the secondaryexhaust thrust 180° such that both the LAP 92 primary and secondarythrusts flow along a plane of positive thrust in the K direction that isapproximately parallel with the LAP 92 first and second side panels 86and 90. Additionally, in various embodiments, the LAP 92 is operatedsuch that each pulsejet cell 98 is operated effectively 180° out ofphase with adjacent pulsejet cells 98. For example, if the LAP 92included eight pulsejet cells 98 sequentially numbered from one end ofthe LAP 92 as pulsejet cells 1, 2, 3, 4, 5, 6, 7 and 8, as illustratedin FIG. 6A, pulsejet cells 1, 3, 5 and 7 would substantiallysimultaneously operate 180° out of phase with the substantiallysimultaneous operation of pulsejet cells 2, 4, 6 and 8. Moreparticularly, when pulsejet cells 1, 3, 5 and 7 are in the compressionphase of the propulsion cycle, pulsejet cells 2, 4, 6 and 8 aresubstantially simultaneously in the combustion phase, and vice versa.

Furthermore, when the air/fuel mixture combusts in the combustionchamber sections 110′ of each pulsejet cells 98, the high pressureprimary exhaust is discharged from the respective nozzle sections 106′creating a high pressure zone at the end of each respective nozzlesection 106′. Because all adjacent pulsejet cells 98 are 180° out ofphase, the adjacent pulsejet cells 98 are substantially simultaneouslyin the compression phase drawing air into the respective combustionchamber sections via the LAFP 118. As previous combustion results inreduced combustion chamber pressures a significant pressure differentialexists between the respective combustion chambers 110′ and the ends ofthe respective nozzles 106′. More significantly, by having the adjacentpulsejet cells 98 180° out of phase, the high pressure zones at the endof pulsejet cells 98 in the compression phase is multiplied due to theadjacent pulsejet cell(s) 98 simultaneously discharging primaryexhausts. Thus, the pressure differential between the respectivecombustion chambers 110′ and the ends of the respective nozzles 106′ ismultiplied. This increased or multiplied pressure differential willcreate significantly larger compressive forces within each combustionchamber section 110′ during the respective compression phases andgenerate higher combustion efficiency for each pulsejet cell 98.

As best shown in FIG. 6C, the linear helmet 114 includes a plurality ofdividers (webbing) 122 that are located within the linear helmet 114 tosubstantially align with the intercostals 94. The dividers 122 directair/exhaust flow into and away from the individual pulsejet cells 98through the LAFP 118. In various embodiments, the LAP 72 includes a pairof linear nozzle flaps 124 located at the end of the nozzle section 106,shown in FIG. 6, that pivot to control the primary exhaust flow exitingeach pulsejet cell 98. The nozzle flaps 124 are pivotal between a closedposition, in which the exhaust nozzles 106′ of each pulsejet cell 98 arecompletely closed off, and in a full open position, in which the nozzleflaps direct entrained airflow through flap gaps 128 between the nozzleflaps 124 and the nozzle section 106.

Referring particularly now to FIGS. 7 and 7A, in various embodiments thefirst and second side panels 86 and 90 of body 82 have an undulating,i.e. wave-like or corrugated, form having a plurality of linear ridges126 and linear valleys 130 that extend a height L of the body 82 . Eachof the intercostals 94 connects between the first and second side panels86 and 90 at opposing linear valleys 130 so that each pulsejet cell 98has a quasi-cylindrical or quasi-oval form. That is, each pulsejet cell98 will have opposing curved walls comprising respective portions of thefirst and second side panels 86 and 90 and opposing flat wallscomprising two of the intercostals 94. Alternatively, the first andsecond side panels 86 and 90 could have an undulating form only at thecombustor section 110 of the LAP 82. The linear valleys 130 provide AFPs30 between the linear helmet 114 and the exterior of the body sidepanels 86 and 90 that allow increased air flow into and out of eachpulsejet cell inlet 102′.

Referring now to FIG. 8, in various embodiments, the LAP 82 is mountedwithin a LAP augmentor 142. The LAP augmentor 142 includes a pair ofopposing entraining walls 146 adapted to entrain ambient air combinedwith the LAP 82 primary and secondary exhausts to maximize propulsionthrust from each of the pulsejet cells 98. The entrainment walls 146 canhave any shape suitable to entrain the ambient air. For example, theentrainment walls 146 can be flat or the entrainment walls 146 can becurved, as shown in FIG. 8. The LAP augmentor 142 additionally includesa pair of opposing end walls 150 connected to and substantiallyorthogonally between the entraining walls 146. The LAP 82 can be mountedwithin the LAP augmentor 142 using any suitable mounting means,component, device or structure. For example, the LAP 82 can be mountedto one or more of the LAP augmentor entraning walls 146 and/or the endwalls 150 using one or more of bridge fairings 154. In variousembodiments, the end walls 150 include a plurality of apertures 158adapted to allow a portion of the entrained air and the LAP primary andsecondary exhausts to exit the LAP augmentor 142 in a cross flowdirection M.

The LAP 82 is connected to the LAP augmentor 142 such that unimpededplanar gaps or spaces are created between the entraining walls 146 andthe LAP side panels 86 and 90. Entraining low velocity ambient air withthe high pressure, high velocity primary and secondary exhaust of eachpulsejet cell 98, will substantially increase the thrust generated byeach pulsejet cell 98. For example, the LAP augmentor 142 caneffectively double the thrust generated by each pulsejet cell 98. Itshould be understood that it is with the scope of the invention for theaugmentor 142 to include the embodiment of the LAP 82 illustrated inFIG. 6.

FIG. 8A is an isometric view of the LAP 82 and LAP augmentor 142,wherein the augmentor entraining walls 146 include auxiliary inlet flaps132, in accordance with various embodiments of the present invention.The inlet flaps 132 are pivotal between a closed position, in which theentraining walls 146 substantially have the form shown in FIG. 8, andvarious open positions in which an auxiliary air intake opening 164 isprovided. The size of the auxiliary air intake opening 164 is variablebased on the position of the auxiliary inlet flaps 132. The auxiliaryair intake openings allow auxiliary air flows into the LAP augmentor 142that supply intake air to the LAP 82. When the auxiliary inlet flaps 132are in the closed position, all air supplied to the LAP 82 is providedthrough the open top of the LAP augmentor 142. Depending on the openposition of the auxiliary inlet flaps 132, air supplied to the LAP 82via the open top of the LAP augmentor 142 will be varyingly reduced.That is, the further open the auxiliary inlet flaps 132 are, the moreair will be supplied to the LAP 82 through the auxiliary air intakeopening 164. This allows the air flowing through the top of the LAPaugmentor 142 to increasingly be used to cool the LAP 82. The auxiliaryinlet flaps 132 and the auxiliary air intake opening 164 can be ofvarious designs to accommodate specific aircraft integration, and remainwithin the scope of the invention.

For clarity of FIG. 8, the side panels 86 and 90, and the intercostals94 of the LAP 82 are illustrated by a single solid or dashed line.However, it should be understood that the side panels 86 and 90, and theintercostals 94 have a thickness sufficient to withstand the heat,stresses and forces the panels 86 and 90, and the intercostals 94 areexposed to during operation of the aircraft and the LAP 82.Additionally, in various embodiments, the LAP augmentor 142 isincorporated into the structural framework of the aircraft, e.g. a VTOLaircraft, as an integral load bearing structural member of the aircraft.For example, in various embodiments the LAP augmentor entraining walls146 and the LAP side panels 86 and 90 can functions as keel structuresof an aircraft fuselage and the bridge fairings 154 can also function asa load bearing structure for such things as propulsion and/or aircraftloads. In various embodiments, a plurality of LAPs 82 including LAPaugmentors 142 can be joined side-by-side. In which case the centeraugmentor wall 146 could be omitted or formed as a flat partitionbetween the LAPs 82.

Referring now to FIGS. 9, 9A, 9B and 9C in various embodiments,intercostals 94 are double walled partitions having a pair of walls 160.In various other embodiments, the walls 160 have an air gap 162 betweenthem through which cooling air passes to cool the pulsejet cells 98.Cooling the pulsejet cells 98 adds to the life or survivability of thematerial used to fabricate the LAP 82 and to reduce the absorption ofheat into the aircraft structure. Additionally, the helmet dividers 122are double walled dividers having a pair of walls 166 and an air gap 168between the walls 166 through which air can flow into the double walledintercostals air gap 162 to cool the pulsejet cells 98, as shown in FIG.9C. Although the intercostals air gaps 162 are illustrated in FIG. 9 tobe approximately rectangular, in various embodiments the walls 160 ofthe double walled intercostals 94 are configured to form the pulsejetcells 98 having rounded corners, as shown in FIG. 9B. That is, thepulsejet cells will have an effectively oval cylindrical or roundcylindrical shape. The rounded corners will improve the aerodynamics andcombusting efficiency of the LAP 82.

The LAP 82 described above provides a high thrust to weight ratio, lowfuel consumption, highly effective low weight thrust system foraircraft, for example VTOL aircraft. Additionally, the LAP 82 andaugmentor 142 can be incorporated as an integral load bearing structureof the aircraft. That is, the LAP 82 and augmentor 142 are totallyintegrated as a permanent aircraft structure used for carrying aircraftand propulsion loads. Furthermore, the linear aspects of the integrationof the LAP 82 and augmentor 142, as a component of the aircraftstructure, will promote more predictable mass flow entrainmentcharacteristics.

Those skilled in the art can now appreciate from the foregoingdescription that the broad teachings of the present invention can beimplemented in a variety of forms. Therefore, while this invention hasbeen described in connection with particular examples thereof, the truescope of the invention should not be so limited since othermodifications will become apparent to the skilled practitioner upon astudy of the drawings, specification and following claims.

1. A pulsejet comprising: an inlet; an exhaust nozzle; a combustionchamber between the inlet and the exhaust nozzle; and a flow-turningdevice positioned over an end of the inlet to form an air flow pathway(AFP) having a substantially 180° turn for aligning a direction ofexhaust exiting the combustion chamber through the inlet to besubstantially parallel with exhaust exiting the combustion chamberthrough the nozzle along a positive axial thrust line.
 2. The pulsejetof claim 1, wherein the AFP ensures returning inlet reflection wavesmeet returning nozzle reflective waves within the combustor chamber. 3.The pulsejet of claim 1, wherein an outside diameter of a side wall ofthe flow-turning device is approximately 100% to 125% as long as anoutside diameter of the combustion chamber.
 4. The pulsejet of claim 1,wherein the pulsejet further includes a straight inlet section extendingfrom an end of the combustion chamber opposite the exhaust nozzle, thestraight inlet providing an AFP area ratio that expands as a side wallof the flow-turning device extends toward the combustion chamber andnozzle.
 5. The pulsejet of claim 4, wherein the straight inlet sectioncomprises a length to diameter ratio that acoustically tunes thestraight inlet section.
 6. The pulsejet of claim 1, wherein theflow-turning device is formed so that as a side wall of the flow-turningdevice extends toward the exhaust-nozzle, the air gap area between theflow-turning device side wall and the inlet nozzle increases to allowmore air flow into the inlet during the compression phase and diffusethe exhaust exiting the combustion chamber through the inlet during thecombustion phase.
 7. The pulsejet of claim 1, wherein the combustionchamber has an elongated cruciform shape including a plurality of linearapexes and linear valleys that create a plurality of AFPs between a sidewall of the flow-turning device and the valleys that provide effectivelyunimpeded air intake flow and exhaust flow into and out of the inlet. 8.A method for providing vertical take off and landing propulsion for anaircraft, said method comprising: providing at least one valve-lesspulsejet integrated within a fuselage of the aircraft, the pulsejetincluding a body having an inlet, an exhaust nozzle, a combustionchamber between the inlet and the exhaust nozzle; and positioning aflow-turning device over an end of the body to form an air flow pathway(AFP) having a substantially 180° turn for aligning a direction ofexhaust exiting the combustion chamber through the inlet to besubstantially parallel with exhaust exiting the combustion chamberthrough the nozzle along a positive axial thrust line.
 9. The method ofclaim 8, wherein positioning a flow-turning device over the end of thebody comprises forming the flow-turning device to have an outsidediameter that is approximately 100% to 125% of an outside diameter ofthe combustion chamber.
 10. The method of claim 8, wherein providing thevalve-less pulsejet comprises providing an AFP area ratio that expandsas a side wall of the flow-turning device extends toward the combustionchamber and nozzle by providing a straight inlet section extending froman end of the combustion chamber opposite the exhaust nozzle.
 11. Themethod of claim 10, wherein the straight inlet section comprises alength to diameter ratio that acoustically tunes the straight inletsection.
 12. The method of claim 8, wherein positioning a flow-turningdevice over an end of the body comprises increasing air flow into theinlet during a compression phase and diffusing the exhaust exiting thecombustion chamber through the inlet by forming the flow turning devicesuch that an area of the AFP increases as a side wall of theflow-turning device extends toward the exhaust nozzle.
 13. The method ofclaim 8, wherein providing at least one valve-less pulsejet comprisesforming the combustion chamber to have an elongated cruciform shapeincluding a plurality of linear apexes and linear valleys that create aplurality of AFPs between a side wall of the flow-turning device and thevalleys that provide effectively unimpeded air intake flow and exhaustflow into and out of the inlet.
 14. A vertical take off and landing(VTOL) aircraft, said aircraft comprising: a fuselage having integratedtherein at least one valve-less pulsejet, the pulsejet comprising: abody having an inlet, an exhaust nozzle, a combustion chamber betweenthe inlet and the exhaust nozzle; a flow-turning device positioned overan end of the body to form an air flow pathway (AFP), the flow-turningdevice adapted to direct intake air flow into the inlet and exhaust flowexiting the combustion chamber through the inlet; and an augmentor cellconnected to the body, the augmentor cell including includes a pair ofopposing entraining walls adapted to entrain ambient air with exhaustflows of the pulsejet to maximize a propulsion thrust from the pulsejet.15. The aircraft of claim 14, wherein the flow-turning device forms theAFP to have a substantially 180° turn for aligning a direction of theexhaust exiting the combustion chamber through the inlet to besubstantially parallel with exhaust flow exiting the combustion chamberthrough the nozzle along a positive axial thrust line.
 16. The aircraftof claim 14, wherein the AFP ensures returning inlet reflection wavesmeet returning nozzle reflective waves within the combustor chamber. 17.The aircraft of claim 14, wherein an outside diameter of a side wall ofthe flow-turning device is approximately 100% to 125% as long as anoutside diameter of the combustion chamber.
 18. The aircraft of claim14, wherein the pulsejet further includes a straight inlet sectionextending from an end of the combustion chamber opposite the exhaustnozzle, the straight inlet providing an AFP area ratio that expands as aside wall of the flow-turning device extends toward the combustionchamber and nozzle.
 19. The aircraft of claim 18, wherein the straightinlet section comprises a length to diameter ratio that acousticallytunes the straight inlet section.
 20. The aircraft of claim 14, whereinthe flow-turning device is formed so that as a side wall of theflow-turning device extends toward the exhaust-nozzle, the air gap areabetween the flow-turning device side wall and the inlet nozzle increasesto allow more air flow into the inlet during the compression phase anddiffuse the secondary exhaust during the combustion phase.
 21. Theaircraft of claim 14, wherein the combustion chamber has an elongatedcruciform shape including a plurality of linear apexes and linearvalleys that create a plurality of AFPs between a side wall of theflow-turning device and the valleys that provide effectively unimpededair intake flow and exhaust flow into and out of the inlet.